I'm not sure this answers your question, but I've never seen a decent explanation for what upsampling is. All CD players since the 1980s interpolate data, that is, they create virtual samples in between the ones at 44.1 khz. This helps with the D/A conversion, but doesn't create any new information. This is sometimes called "oversampling." I don't get how oversampling is any different, or why it should be better.
